Rheostat



,Patented Feb." 15, 1927.

WILLIAM K'ArsLINceor omesso, rLLrNois, AssreNoR To KnLLoGG swrroHBoAnn1,618,015 PATENT. oFFICE.

AND SUPPLY' COMPANY, 0F CHICAGQILLINOIS, A CORPORATION OF ILLINOIS.

RHEOSTAT.

Application iiled October 8, 1923. Serial No. 667,093.

fr '.-My invention relates to rheostats for varying the-`resistance inlan electric circuit Y,and is adapted particularly foruse in controllingthev4 filament of. electron tubes and ianobje/ctof my invention is toprovide a vrheostat which is simple in construction but very durablevland etiicient. n

Rheostats of the type employed in use for "controlling the current iiowthrough the filament `oi an electron tube are usually provided ywith acontact wiper and when the rheostat is operated to increase or decreasethe amountof resistance in the circuit in whichthe'rheostat is used,this increase or decrease in the amount of resistance is eifyf ected .byavcomplete turn ci the convoluti'ons-of vthey resistance coil.This'means oi adjustment is objectionable in that it is dii- 'cult insome instances to obtain the proper Vamount ofresistance in theoperating circuit. To overcome this objectionable feature I havevdesigned an improved rheostat and a l 'feature of'my invention vis theprovision of "a vernier-attachment in the form of a single rt-urn' ofwirel'equal'to several turns of the 'fmarn resistance element) in seriesrelation with the resistance coilv of the rheostat and an 1 auxiliarylwiper associated therewith.

Another` `feature of my invention is the method offcontrolling themovement of the wiper associated with the Vernier turn of wire to placethe same in contact therewith,

and the movement or" the wiperassociated with the main resistance coil.The movement of the wiper of the resistance coil and 1 Iwiper ofthevernier wire is under the con- ',trol of a singleunit, which vafterhaving been moved a certain degree may be rotated in either direction alimited distance without effect-ing the movement of the Wiperassocia-ted with the main resistance coil and bring about the movementofthe wiper as- 2 sociatedwith thevernier wire to further in- 1 creaseorfdecrease the resistance.

suing speciiication, `and for a more complete j understanding'ot thesame, reference mayY 'lfbe lhad to Athe accompanying drawing, v'1n.which like reference characters in the sev.-

i l'eral views .denote like parts and in which;

; Another lfeature of my invention is theV F 1 is a front view of therheostat ot my invention illustrating it in Lits normal or oil position.

Fig. 2,is a right side view of Fig. l;

Fig. 8 'is a sectional view along the line 8 3 ot Fig. l;

Fig. Ll is a back plan'view of the rheostat;

Fig. 5 is a sectional view along the` line 5 5 of Fig. 2, and

Fig. 6 is a view similar to Fig. 5 but showing the rheostat in its olfnormal or on position.

Referring now more in detail to my invention as illustrated in theaccompanying drawing, the rheostat of my invention comprises aresistance coil or unit 2 of a predetermined ohmic resistanceV woundupon a iiat strip o'i' insulating material 3, by suitable machine means,its ends 6 and '7 passing through suitable orifices in the strip 3 forholding purposes. The strip 3 which carries the resistance coil 2 afterbeing wound is now formed intoV a substantially ring shaped member R bymeans of a suitable torming operation and its ends 6 andv 7 are thensecured to an arcuate shaped yoke iember 8 by means of the screws 9 and10. rfhe screw 9 passes through a suitable oriiice in the end 6 of themember .R and eX- tends through the yolre 8 but insulated therefrom bymeans oi an insulating bushing 11, and a nut 12 having screw threadedengagement with the screw 9 secures the end 6 to the yoke 8. One end 4of the resistance coil 2 is securet to the screw 9 and a terminal 13resting between-the nut 12 and bushing 11 provides connecting' means totheA resistance coil or unit 2. The screw passes through suitableoriiices in lthe end 7 oi the member R and yoke 8 but .insulated fromthe yolre 8 by anv insulating bushing 14, and a nut 15 having screwthreaded engagement with screw 10 secures the end 7 of the member R tothe yoke 8. A terminal 16 rests between the bushing 11i and the nut- 15for the usual connection means. K

The arcuate yoke member 8 is provided with a pair ot integrally formeddepending arms 17 and 18 substantially; parallel with each other Vforsupporting the rotatable shaft 19.' l' provide a U shaped wiper member Bwhich rests between-the arms 17 and 18 and itswiper arms 2O and 21engage re- `19 extending through the V32as a whole is secured to the arm1S of t spectivelyv the peripheral portions of the convolutions of theresistance unit 2 and are formed to provide a spring effect for grippingthe convolutions of the coil 2 so as to insure a good contactualengagement between the wiper arms 20 and 21 and the convolutions of thecoil. yThe bridge 41 of the U shaped wiper member B is provided with alongitudinal slot 42 and a screw 43 having screw threaded engagementwith the shaft slot 42and effects the rotation of the wiper member B aswill present-ly be. described. rlfhe rotatable shaft 19 is provided witha reduced portion 19 which passes through suitable orifices 26 and 27.in the arm 17 of the yoke 3 and wiper varm 2O ofthe wiper member B andorifices 28 and 29 of the wiper arm 21 of the wiper inemher B and Varm13 of the yoke member The vernier unit V of the rheostat of my inventioncomprises a disc 30 of suitable msulating material and secured to itsface near its peripheral edge is a turn of wire 32,

.its one end ,passing through a suitable orifice in the disc 30aiid bentto secure the same to the disc 30. The other end also passes through anorifice in the disc 30 and is in turn soldered to the terminal 15 forpurpose. as will presently be described. Intermediate ofthe ends of thewire 32 the said wire rests in a slot of a pin 33 to hold the sameagainst the disc 30 and also maintain its circular shape. The disc 30and its wire il() yoke member 8 by means of a screw 35 which screw hasscrew threaded engagement with. a suitable tapped orifice in the arm 13.1 also provide a- Wiper 36 which is adapted to contact with the wire 32the said wiper being secured to a lug 37, which lug 37 is provided witha central orifice 38. The disc 30 is provided with a central orifice 39through which the reduced portion 19 of the shaft 19 protrudes and is ofa size to permit the lug 37 and its wiper 36 to be slipped over theshaft portion 19 as a whole and secured thereto by means of the setscrew 40. The shoulder formed by the reduced portion of theshaft 19rests against the face of the arm 17 of the yoke S and the lug 37 towhich the wiper 36 is secured is fastened to the shaft 19 to preventlateral movement of the shaft 19 but permits its rotation. A. knob K issupported on the shaft 19 for rotating the same and for a detaileddescription of the method of supporting the knob refeence may be had toan application of Emil J. Nielsen, Serial No. 603,927 tiled Nov-cmber29, 1922.

1 `lVl1en the wiper arms 20 and 21 of the wiper member B associated withthe resistance unit 2 and the wiper 36 associated with the vernierresistance unit V are in their ofi' or normalposition lthey are in theposition as clearly illustrated in Figs. 1, 4tV and 5, To

operate they rheostat of my invention the knob K is grasped and rotatedin a clockwisedirection with reference to Figs. 1, 5

and 6 causing the shaft 19 to-be rotatedand as thewiper` 36 of theVernier unit V is se- 70 cured to the shaft 19 by means of the set screw40 itI is also rotated causing it to contact with its vernier resistance32. The U shaped wiper member B is not rotated as it is loose on theshaft 19 and the first movenient of the shaft 19 from its off positiononly effects the travel of the wiper 36 of the vernici* unit V and thedegree of travel of the wiper 36 before the wiper member B is rotated isgoverned by the length of the slot 42 in the bridge 41 of the wipermember B. Now as the shaft 19 continues rotating the screw 43r securedto it rotates through a predetermined degree of rotation governed by thelength of theslot 42 before the movement of the wiper arms 20 and 21 isbrought about. 1n the rheostat of my invention the shaft 19 travelsthrough approximately ninety degrees of rotation before the screw 43which extends through the slot 42 engages the edge 4 4 of the slot 42 inthe bridge 41 of the wiper member' B as clearly villustrated in Fig. 6.The further rotation of the shaft' 19Y now brings about the rotation ofthe wip-er member B causing the wiper arms 2() and 21 thereof to engagethe convolutions of the resistance unit 2, the Wiper 36 of the vernici'unit V being also rotated. lVhcn the knob K is rotated in a clockwisedirection the wiper varms 20 and 21 engage successive convolutions ofthe resistance unit 2,

causing the resistance of the electrical circuit inwhich the rhecstat isused to he dccreased and when the proper coarse adjustment is obtained,a finer adjustment may be obtained by the use of the vernici' unit V ofthe rheostat of my invention.

From the above description it may be seen that the wiper 36 of thevernici: unit V is approximately ninety degrees in advance of the wiperarms 20 and 21 of. the wiper member B associated with the resistanceunit 2 as the shaft 19 is rotated from its oii' position before thewiper member B is moved 'to engage the first convolutions of theresistance unit 2. Thus as the wiper member B is moved from its offposition to its extreme on position iu which position practically all ofthe resistance unit f2 is out out the wiper member B has traveledthrough ap- FLW? proximately two hundred and seventv de- `grees ofrotation and as the wiper of the i' trontubethere isa critical'pointatwhich c theitube will work at itsma-Ximum efliciency .Cency i :N'Owhas been'ladJusted as above described to yflfp'lace the wiper arms20a-nd. 21 in position cutv'in OI'Out obtain this maximun'i ei'ii- 'whenthe rheostat of my invention 'onfthe resistance unit 2 so". that theapproxifmateamouiitiof resistance has been cut in vthe circuit Iprovide'the Vernier unit V whereby the further rotation'of the wiper 36of thevernier unitVv 'may bev rotated in a counter clockwise orclockwise direction to .further increase Ior decrease the resistanceuntilrjust thenriolit amount of resistance is ucutin the circuit as willnow be described, v'After the wiperarms. 2O Aand 21 have been adjustedto approximately out in the proper amount of resistance of the unit 2after having' rotatedr the `'shaft' 19 in a clockwise direction, theknob K may -now be rotated in v.a counter clockwise direction throughapproXimately ninety degrees of rotation withoutfdistiirbing ltheladjustment of the wiper @arms 20.*and 21 ofthe wiperY member B as theWiper member islooseup'on the shaft 19 and ,a'sfthey wiper36oftheVernierunit is lined to thej'shaftjl)4 this counter' clockwise rotation of theshaft 19 causes the wiper to rot-ate in thisfdirection andY wipe overthe .wire 32 of the Vernier unit V. The distance traveled by the Ywiper3G vover the wire inr its counter clockwise direction throughitsfninetyldegrees of 'rotation may beapf Lproximately"the lengtlifofone or two conis moved over the wire 32 in this counterclockwisedirect-ion it A may be placed in an i infinite number ofpositions oiithat portion ofytfhe wire 32 that is covered by the wiper 145'l grecsV of counter clockwise rotation.

36 in its course" ofl travelin its ninety dey lt is .i also"readilyapparent that the wiper 36 of k the vernier unit V may berotated in either axcloclrwise or counter clockwise direction in thisninety degreesv without disturbing the fadjustinent of the wiper arms 2Oand 21 of the/wipermeinber B'that is in its adjusted position.

If vin rot-ating the wiperginember D i) lS "farms and 21 are rotatedbeyond the approximate pointfof the proper amount of resistance to beused', the knob K is turned in a counter clockwise direction causing theshaft'19 to also rotate in a counter clockwise direction until the screwL13 securedto the shaft the wiper 36of the Vernier unit V also travelsin this direction. Further rotation of the shaft 19 in this Vdirectionafter the screw 43 has engaged the edge 45 ofthe slot l2 causes thewiper member B to be' rotated in a counter clockwise direction causingthe wiper arms to enga-gesuccessive convolutions of the resistanceunitj2 until the approxi-' mate amount of resistance is cut in and toobtain a finer adjustmentthe Shaft may vnow be rotated in a vclockwisedirection through ninety degrees of rotation to permit f the wiper 36 oft-hev Vernier unit V to be rotated over the portion of the wire 32Ycovered by the degree of rotation of the vwiper 36, f A

also provide means for holding Ythe wiper arms 2O and 21 in theiradjusted'position and to insure good electrical contact, as will now bedescribed. The face of eaclifwipei" arm 20 and 21 is provided with anintegrally formed tongue portion 46 which projects slightly above theface of each4 arm 2O and 21 :io that when the wiperl member B isinserted between the, arms 17 and 18 ofthe yokeV ber B is in positionengage the inner faces of the arms l? and 18 thus producing frictionalholding means for holdingthe wiper arms 2G and 21in theiradjustedpositionand for insuring good electrical cont-act, The wiper 3Sof the vernier unit Vis also provided with a frictional holding meansfor lholding the wiper 36 in itsadj usted position.` The wiper 36 isvprovided with an integrally formed arm L18, diametrically opposite itand when the wiper 36 is secured in posit-ion on the shaft 19V the arml8'engages the face of the disc and the tension ofthe arm 48 is Asuch asto produce frictional holding means between the arm li8 and face of thedisc 30 to hold the wiper 3G in any of its adjusted positions, and to obviatc a side thrust on the shaftof the device. lThe two' arms insuregood electrical contact of the wiper on wire 32 Vand at the same timeprevents a sido thrust on the shaft.V The wiper member B is limited inits oifposition by means of the screw 35V which secured thedisc 31 tothe arm 18 of the yoke 8; This screwwprojects through the arm 18 and Yisengagedfby the i wiper arm21 when the wiper member B is moved to itsoftposition to limit its movement in that direction.` T he wiper arm 21also engages the screw 35 when the wiper member B is moved its extremeon position to limit the movement of the wiper member B in thisdirection, thus the screw 35 which secures the disc 31 in position onthe arm 18 of the yoke 8 also serves as a stop for the wiper membei'B. A

In Fig. Y.3 l illustrate the ilieost-aty mounted upon a panel sliown'indotted lines by means of a screw 51 whichY extends through a' suitableorifice in the panel and has screw threaded engagement with a suitabletapped rio orifice 52 inthe arm 17 of the yoke member 8.

From the foregoing it is apparent that my device is so arranged that bysimply turning the control knob the turns o-f wire on the main rheostatmaybe cut in or out and by a movement of the same knob the vernier wipermay be madeto move over its turn of wire for the fine adjustment.

While I have described a preferred embodiment of my invention it ist-obe understood that'I do not wish tobe limited to the'exact structure asshown and described, as changes will readily suggest themselves, and Itherefore aim to cover all such changes and modifications as come withinthe spirit and scope of the appended claims. Y

What I claim as new and desire to secure by United States LettersPatent, is as follows l. A device'of the character described including asupporting yoke, aresistance unit supported by said yoke, a wiperoperatively associated with said resistance unit, a shaft for rotatingsaid wiper, a second resistance unit supported by said yoke, and a wiperopera-tively associated with said second unit, a shaft for adjustingsaid wipers, said lirst wiper having integrally formed means consistingof a tongue member adapted to engage saidsupporting yoke to maintain thesame in any adjusted position, said second wiper having integrallyformed means consisting of an extending portion adapted to yengage asupporting member to maintain the same in any adjusted position, andcontrol means permitting the rotation of the wiper of said secondresistance unit by said shaft from its adjusted position withoutaffecting the adjustedV position ofthe wiper of said first unit.

2. A device of the. character described including va supporting yoke, aresistance unit supported by said yoke and a wiper associated therewith,Ya second resistance unit supported by said vyoke and a wiper associatedtherewith, a shaft for advancing said wipers into engagement with theirrespective resistance units, said iirst wiper having integrally formedmeans `consisting of a tongue portion adapted to engage the said yokemember to maintain the .said wiper in any adjusted position, and controlmeans to permit the movement of said second wiper in a clockwisedirection or counter clockwise direction a predetermined degree withoutaffecting the rotation of said iirst wiper.

3. .A device of thejcharacter described including a rotary shaft, amounting member supporting said shaft, a pair of resistance elementsdirectly supported by said mounting member, a pair of contact elementsfor contacting with said resistance elements, one of said contactmembers being directly connected to said shaft, and the other `memberbeing loosely supported thereby so that the first contact member mav bemoved a predetermined distance without moving said second contactmember, one of said contact inembers having integrally formed meansconsisting of a tongue portion adapted to engage said mounting member tomaintain said wiper in any adjusted position, said other contact memberhaving integrallv formed means consisting of an extending portionadapted to engage said mounting member to maintain said wiper in anyadjusted position.

4. A device of the character described including a mounting member, apair of relatively stationaryresistance elements connected to saidmounting member, a rotary shaft supported by said mounting member, adouble wiper for engaging one of said resistance elements and a singlecontact 35 said single contact wiper in any adjusted position.

5. A device of the character described including a plate of insulatingmaterial, a resistance element connected thereto, a double ended wiperhaving its one end adapted to engage said resistance element and itsother end adapted to engage said plate of insulation to providefrictional means to maintain the wiper in said engagement with saidresistance element, and a member for moving said wiper over saidresist-ance element.

6. A device of the character described including a mounting member, aresistance element supported thereby, a rotary shaft supported by saidmounting member, a wiper having a slot, a member extending through saidshaft into said slot whereby the shaft may be rotated a predetermineddistance while permitting the wiper to remain Stationary and yieldingcontact means consisting of an integrally formed tongue portion adaptedto co-act between said wiper and said mounting plate to maintain thewiper in any position to which it is rotated.

Signed by me at Chicago, in the county Cook and State of Illinois, this4th day of Getober, 1923.

IVILLIAM KAISLING.

